Header overflow

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John H
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Header overflow

Post by John H »

Wonder if anyone has any ideas on this new development! I completed the cam break in where the engine did get to 240F before I shut her down. Changed oil filter etc. During the break in I noticed the thermostat housing was leaking - dripping, so I drained some of the coolant out to change the gasket, refilled the system. All was well no leaks from the new gasket, just an annoying wetness from the temp switch. But she has now developed a leak from the header cap when running. I have a Stant 18-22lbs Lev-R-Vent cap. Using Evans I believed there should be minimal pressure developed so why would the cap vent? Looking at the cap the rubber seal on the venting mechanism does look odd, I may be imagining it, but could the Evans be effecting the cap? There was no problem during the break in and the engine has never got that hot again. Any ideas? Plan is the order a new cap - should I go for standard no vent version??

I remember Karl mentioning to me problems of lost fluid before he added a MBG vent bottle that collected the fluid and allowed it to be taken back when cooled....
Thanks in advance!
Built St Piran Hawk289FIA in Scotland!
Karl
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Re: Header overflow

Post by Karl »

You have the main flow going through the tank? If yes John, modify it as I said. Johannes had the same problem this summer, he looked at my version and is changing this winter or has already changed his system.
Regards Karl
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peterc
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Re: Header overflow

Post by peterc »

My understanding of the need for a vent/ overflow bottle is that when the coolant gets hot it expands and rises in the header tank then pushes out of the vented cap. This is not helped if the header needs to be 100% full when cold to get the coolant level high enough to ensure the system is free of air in the heater.
Rather than allow the coolant to drop onto the ground you drop it into an over flow bottle. I use a cap without a spring seal on the header and have the pressure venting cap on the overflow bottle as per MG Metro/ Mini. The system is set up with the overflow 1/3 full. When the engine heats up the bottle is 2/3rds full and when the engine cools it sucks it back up.
I have no experience with Evans but assume the physics of expansion is the same.
I have no doubt Roger will advise on his set up with Evans.
Peter C
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Re: Header overflow

Post by Karl »

System as Peter has it.
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Re: Header overflow

Post by Johannes1 »

Two pics, how to lose overheating:
Image

this is Karls and Peters way

Image

and this is how i have done, hopefully it works,
In the cold winter weather i have no chance to check, if not i´ll do like Karl

Regards
Johnnes
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Re: Header overflow

Post by Karl »

Where is the blue connection at the bottom going to Johannes?
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Re: Header overflow

Post by Johannes1 »

Hi Karl,
happy and healthy new year.
The blue part is no connector it is only a lock. (Verschluß ohne jegliche Funktion)
Johannes
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Re: Header overflow

Post by Karl »

Thank you, same to you (and all the others)
So the hose on the upper side is connected to the radiator? If yes, I would suggest to connect this to the lower connector, so there is no chance to suck any air back into the system. If the header tank always has a waterlevel above the connection it should work.
Regards
Karl
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John H
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Re: Header overflow

Post by John H »

Thanks all. It may be that I added more coolant second time around hence the expansion only manifesting itself now. I see the 'T' option on the smaller rad pipe as a good option. MG parts here I come!
Built St Piran Hawk289FIA in Scotland!
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clive
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Re: Header overflow

Post by clive »

Hi John, how full was the expansion tank when you refilled the system? If it is like mine the coolant level is no higher than the top of the inlet hose so probably just over half full. I have found from experience that if I fill it higher it will vent out of the overflow and when cool the level settles back to the top level of the inlet hose. If I remember correctly my cap pressure is about 14 lbs. Perhaps your cap pressure is too high and the pressure is looking for the weakest point to escape, in your case the thermostat gasket initially and then the cap vent.

Image
Last edited by clive on Wed Jan 04, 2017 11:02 pm, edited 1 time in total.
Cheers, Clive.

(If I'm not here I'm in my workshop or on the golf course!)
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